Loans - Schedule of Recorded Investment in Impaired Loans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	$ 15,201.6	$ 17,844.9
Financing Receivable, Accrued Interest, Writeoff	(3.4)	(4.1)
Collateral
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	102.1	97.6
Collateral | Commercial Real Estate Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	33.5	47.3
Collateral | Real Estate Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	3.8	3.2
Collateral | Agricultural Real Estate Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	23.8	1.8
Collateral | Real Estate Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	63.7	55.0
Collateral | Agricultural Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	23.4	20.4
Collateral | Residential Real Estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	2.6	2.7
Collateral | Commercial Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	15.0	22.2
Business Assets Pledged as Collateral | Collateral
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	28.7	20.3
Business Assets Pledged as Collateral | Collateral | Commercial Real Estate Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.0
Business Assets Pledged as Collateral | Collateral | Real Estate Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.0
Business Assets Pledged as Collateral | Collateral | Agricultural Real Estate Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.5	0.0
Business Assets Pledged as Collateral | Collateral | Real Estate Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.5	0.0
Business Assets Pledged as Collateral | Collateral | Agricultural Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	22.9	0.0
Business Assets Pledged as Collateral | Collateral | Residential Real Estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.0
Business Assets Pledged as Collateral | Collateral | Commercial Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	5.3	20.3
Real Property Pledged as Collateral | Collateral
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	72.1	76.4
Real Property Pledged as Collateral | Collateral | Commercial Real Estate Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	33.5	47.3
Real Property Pledged as Collateral | Collateral | Real Estate Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	3.8	3.2
Real Property Pledged as Collateral | Collateral | Agricultural Real Estate Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	23.3	1.8
Real Property Pledged as Collateral | Collateral | Real Estate Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	63.2	55.0
Real Property Pledged as Collateral | Collateral | Agricultural Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.5	20.3
Real Property Pledged as Collateral | Collateral | Residential Real Estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	2.6	2.7
Real Property Pledged as Collateral | Collateral | Commercial Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	8.4	1.1
Other Property | Collateral
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	1.3	0.9
Other Property | Collateral | Commercial Real Estate Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.0
Other Property | Collateral | Real Estate Construction Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.0
Other Property | Collateral | Agricultural Real Estate Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.0
Other Property | Collateral | Real Estate Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.0
Other Property | Collateral | Agricultural Financing Receivable [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.1
Other Property | Collateral | Residential Real Estate
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	0.0	0.0
Other Property | Collateral | Commercial Portfolio Segment [Member]
Loans and Leases Receivable Recorded Investment, Impaired [Line Items]
Loans and Leases Receivable, Collateral for Secured Borrowings	$ 1.3	$ 0.8